Neural stimulation has been applied to treat various pathological conditions. Controlled delivery of electrical stimulation pulses to a nerve generates, modulates, or inhibits activities of that nerve, thereby restoring the functions of that nerve and/or regulating the functions of the tissue or organ innervated by that nerve. One specific example of neural stimulation is to regulate cardiac functions and hemodynamic performance by delivering electrical stimulation pulses to portions of the autonomic nervous system. The heart is innervated with sympathetic and parasympathetic nerves. Activities in these nerves, including artificially applied electrical stimuli, modulate cardiac functions and hemodynamic performance. Direct electrical stimulation of parasympathetic nerves can activate the baroreflex, inducing a reduction of sympathetic nerve activity and reducing blood pressure by decreasing vascular resistance. Sympathetic inhibition, as well as parasympathetic activation, has been associated with reduced arrhythmia vulnerability following a myocardial infarction, presumably by increasing collateral perfusion of the acutely ischemic myocardium and decreasing myocardial damage. Modulation of the sympathetic and parasympathetic nervous system with neural stimulation has been shown to have positive clinical benefits, such as protecting the myocardium from further remodeling and predisposition to fatal arrhythmias following a myocardial infarction.
Implantable medical systems are used to deliver neural stimulation. A typical implantable neural stimulation system includes an implantable neural stimulator that delivers electrical stimulation pulses through a plurality of stimulation electrodes. Depending on the location of the nerve to be stimulated, the stimulation electrodes may be incorporated onto the implantable neural stimulator and/or connected to the implantable neural stimulator using one or more implantable leads. In practice, the desirable stimulation sites may not be in a location with anatomical structure allowing for easy implantation of the implantable neural stimulator or easy access by the lead(s). The degree of risk associated with the implantation procedure increases with the degree of invasiveness. Therefore, given a desirable stimulation site, there is a need to minimize the invasiveness of implanting a system that delivers neural stimulation pulses to that stimulation site.